Fernando Alonso says he is expecting a difficult weekend on his return to the cockpit in this weekend's Malaysian Grand Prix.

The Spanish driver missed the first race of the season in Australia as he recovered from his accident during testing at Barcelona, and looks set to race at Sepang once he passes the mandatory FIA fitness tests on Thursday.

McLaren had a tough time in Melbourne, with Jenson Button finishing as the last classified driver in 11th place, two laps down.

The team had to de-tune the Honda power unit in order to make it to the end of the race, and the Sepang weekend is likely to be harder due to the high temperatures.

"The weekend will be tough, but I'm looking forward to getting into the MP4-30 for the first time in a grand prix and getting back to racing," said Alonso in a team preview.

"I've spent some time in the simulator back at the factory with the team, and my focus will be on continuing the development of our package with my engineers, and working on our balance and race set-up.

"There's a lot of potential in the car and we will keep pushing every race until we see results."

Melbourne "encouraging"

Despite the result in Melbourne, Alonso said it was encouraging to see Button reach the end of the race.

"I watched the weekend in Australia very closely and I was in touch with the team from the moment they arrived," he added.

"It's clear we have a lot of work ahead of us but Jenson's result in Melbourne was encouraging from the point of view of reliability and data collection, which are extremely important."

The two-time champion says he feels ready to return to racing after over a month out of the car.

"I've been working hard on my fitness and I feel good and ready to go this weekend," Alonso said.

"The heat in Malaysia is always very tough for the drivers but I've been focusing on this in my training and I'm definitely prepared for all of the weather conditions that we can face in Sepang."